This invention relates to improvements in an apparatus for guiding finite film strip portions during their conveyance, for instance through a developing plant or the like, wherein the film strip portions are individually attached, spaced from one another, to a common carrier strap or belt and project laterally only from a first longitudinal edge of such strap or belt, and wherein the apparatus comprises guiding means having a first longitudinal guiding edge for guidingly engaging a second longitudinal edge of said carrier strap being opposite the said first carrier strap edge, i.e. the carrier strap edge from which the film strip portions project laterally, and wherein the said guiding means also have a second longitudinal guiding edge.
In particular when processing selected portions of a developed photographic film strip, which portions contain a single picture or several adjacent pictures, selected from among the total number of pictures present on the developed strip, and of which portions copies have been re-ordered, they are conveyed through an automatic copying machine; in this case it is conventional to fasten the individual film strip portions at one of their two longitudinal edges on a conveyer strap or belt; or, in the case that the film strips are provided with a lateral re-order tab or label, to fasten them with the free longitudinal edge of such re-order tab on a conveyer strap, in such a manner that the film strip portions protrude laterally from the said strap. The conveying means employed for conveying the film strip portions to the various processing stations engages the carrier strap or belt transporting them, so that the film strip portions themselves, or at least the parts thereof representing the image areas or picture frames, only make contact with parts of the apparatus as little as possible or, preferably, not at all. It is, however, essential that the composite unit which comprises the carrier belt and the film strip portions attached thereto, which latter portions may have affixed thereto re-order tabs or the like, is guided also laterally with great accuracy, so that their exact positioning, for instance, in the illuminating station, is assured.
In a known apparatus of the initially described type the second, free longitudinal edge of the film strip portions serves for the guidance of those longitudinal edges of the film strip portions which are spaced from the carrier strap.
For reasons which will be explained hereinafter, this known guiding means does not offer a sufficiently accurate lateral guidance of the film strip portions. Thus, while the tolerances in transverse extension, or play in bredth, of the film strip portions as well as of the carrier strap can be considered to be so small as to be negligible, it cannot be safely assumed that such narrow tolerances can also be maintained when connecting the film strip portions with the carrier belt, even if such connection is achieved by close abutment of the two members to be joined together; consequently, the play in bredth of the composite unit is enlarged, and the distance between the two longitudinal guiding edges of the apparatus guiding means must be adjusted to fit the largest play expected in the bredth of the composite unit. Moreover, the successive longitudinal edges, of the film strip portions spaced away from the carrier strap, do not form an uninterrupted straight line. Due to this fact, in places where the associated longitudinal guiding edge of the apparatus is interrupted by a gap, the forward free corner (i.e. the corner moving ahead of the next, trailing corner, in the direction of movement of the composite unit) of a film strip portion risks to become caught at this gap in the apparatus guiding edge. Furthermore, these film strip portions are not necessarily of flat shape. Some of them may be curved about an axis which is parallel to their longitudinal direction, thus diminishing the total bredth of the composite unit. Also, the film strip portions to be processed, in particular in successive operations, may be of different bredths depending on their type and standard data. This requires that the known apparatus of the initially described kind be adjusted anew to a determined bredth for each successive processing operation and can only guide accurately during such operation those film strip portions having this preset particular bredth.
In a further known apparatus, the lateral longitudinal guidance is effected solely with regard to the carrier strap. For this purpose, the carrier strap is provided with a conveying and guiding perforation which extends in longitudinal direction in a simple way as in a punched tape, and the holes of which perforation are engaged by the pins of a sprocket wheel. However, even this solution of the guidance problem is not entirely satisfactory. For, on the one hand, bringing about an engagement between the carrier strap and the sprocket wheel requires additional operational steps, while, on the other hand, the carrier strap must be made unduly broad, in particular when the film strip portions bear re-order labels, in order to avoid that holes of the perforation become covered by reorder labels and adhesive tapes. Furthermore, when fitting two carrier straps together, special attention must be paid to the graduations of their respective conveying and guiding perforations. Finally, the costs of a conveyer strap having an accurate conveying and guiding perforation cannot be considered as negligible.